Low dropout regulator and power management circuit

Abstract

The embodiment of the utility model provides a low-dropout linear voltage regulator and a power supply management circuit, which are used for solving the technical problems of complex circuit structure and high power consumption in the technical scheme that the conventional low-dropout linear voltage regulator improves a power supply rejection ratio by copying input ripples at a grid electrode of a power transistor. The low dropout linear regulator comprises an input voltage end, an output voltage end, a band-gap reference source, a resistance feedback network, an error amplifier, an impedance attenuation buffer and a power transistor. According to the differential pressure linear voltage regulator, the impedance attenuation buffer which is simple in circuit structure and low in power consumption is adopted, high-frequency ripple waves, low-frequency ripple waves and noise in control signals are suppressed in a forward attenuation mode, smooth processing of the control signals is achieved, and low ripple waves and high precision of output voltage are ensured. The low-dropout linear regulator is simple in circuit structure and low in power consumption, the power consumption is reduced, the value of the power supply rejection ratio (PSRR) of the low-dropout linear regulator is remarkably increased within the broadband range, and the suppression capacity of power supply noise is enhanced.

Description

Technical Field

[0001] The utility model relates to the technical field of power supply circuits, and in particular to a low voltage difference linear regulator and a power supply management circuit. Background Art

[0002] A low dropout linear regulator (LDO) is a linear DC regulator that converts a fluctuating input voltage into a stable output voltage, and can maintain stability even when the difference between the input and output voltages is small (usually no more than 1 volt). This type of regulator is popular for its low voltage drop, high efficiency, and low energy consumption, and is particularly suitable for noise-sensitive low-noise, high-precision power supply applications, such as powering digital, analog, or radio frequency chips in various electronic devices.

[0003] The low-dropout linear regulator adopts a closed-loop feedback mechanism and consists of an input voltage terminal, a power transistor, a feedback circuit, and an output voltage terminal. The source of the power transistor is electrically connected to the input voltage terminal, the drain is electrically connected to the output voltage terminal, and the gate is electrically connected to the output terminal of the feedback circuit. The input terminal of the feedback circuit is electrically connected to the output voltage terminal, and the conduction degree of the power transistor is adjusted by the control signal input by the feedback circuit to achieve precise output voltage control.

[0004] In extremely noise-sensitive applications such as RF or high-performance analog circuits, the ability to suppress power supply noise is critical. The power supply rejection ratio (PSRR) is an important indicator for measuring the ability to suppress power supply noise. In order to maintain a high PSRR value when the operating frequency increases, the low-dropout linear regulator must be able to maintain a high power supply rejection ratio over a frequency range of several megahertz.

[0005] In order to improve the power supply rejection ratio of low-dropout linear regulators, researchers have proposed a variety of technical solutions, including using RC filters, cascade regulators at the output, and adding isolation measures between the input and output voltage terminals. However, these solutions are mainly effective for low-frequency applications, and have limited effect on improving the power supply rejection ratio in high-frequency applications, and may bring technical problems such as increased power consumption, increased space occupation, and increased voltage drop.

[0006] To solve this technical problem, researchers have developed a new technology solution that uses feedforward technology to improve the power supply rejection ratio. This technology solution uses multiple feedforward amplifiers and summing amplifiers to replicate the negative input ripple at the gate of the power transistor to reduce the control signal gain and eliminate the ripple at the output voltage.

[0007] However, in the process of implementing the technical solution in the embodiment of the utility model, the inventors found that the technical solution of the existing low voltage drop linear regulator to improve the power supply rejection ratio by replicating the input ripple at the gate of the power transistor has at least the following technical problems:

[0008] The circuit structure is complex and the power loss is high. Utility Model Content

[0009] In view of this, the purpose of the embodiments of the utility model is to provide a low voltage dropout linear regulator and a power management circuit to solve the technical problems of the existing low voltage dropout linear regulator that improves the power supply rejection ratio by replicating the input ripple at the gate of the power transistor, such as the complex circuit structure and high power consumption.

[0010] In order to achieve the above purpose, the technical solutions adopted in the embodiments of the present invention are as follows:

[0011] In a first aspect, an embodiment of the present invention provides a low voltage dropout linear regulator, which is applied to a power management circuit; the low voltage dropout linear regulator comprises:

[0012] An input voltage terminal, used for receiving a fluctuating input voltage;

[0013] Output voltage terminal, used for outputting a stable output voltage;

[0014] A bandgap reference source, electrically connected to the input voltage terminal, for providing a reference voltage;

[0015] A resistor feedback network; an input end of the resistor feedback network is electrically connected to the output voltage end, and is used to provide a feedback voltage;

[0016] An error amplifier; a power supply terminal of the error amplifier is electrically connected to the input voltage terminal, a positive input terminal is electrically connected to the output terminal of the bandgap reference source, and receives a reference voltage from the bandgap reference source; a negative input terminal is electrically connected to the output terminal of the resistor feedback network, and receives a feedback voltage from the resistor feedback network; the error amplifier is used to generate and output a control signal based on a difference between a feedback voltage and a reference voltage;

[0017] An impedance attenuation buffer; the power supply end of the impedance attenuation buffer is electrically connected to the input voltage end, and the input end is electrically connected to the output end of the error amplifier, and is used to smooth the control signal transmitted from the error amplifier;

[0018] A power transistor; the source of the power transistor is electrically connected to the input voltage terminal, the gate is electrically connected to the output terminal of the impedance attenuation buffer, and the drain is electrically connected to the output voltage terminal; the power transistor is used to adjust the degree of conduction based on the smoothed control signal and output a stable voltage.

[0019] Optionally, the low voltage dropout linear regulator further includes:

[0020] The voltage stabilizing circuit is embedded between the input voltage terminal and the error amplifier and is used to provide a stable operating voltage for the error amplifier.

[0021] Optionally, the impedance attenuation buffer comprises:

[0022] A source follower, electrically connected to the output end of the error amplifier, for receiving a control signal from the error amplifier and reducing an output impedance of the control signal;

[0023] A current mirror; the input end of the current mirror is electrically connected to the output end of the source follower, and is used to attenuate the ripple and noise in the control signal transmitted from the source follower through an internal impedance;

[0024] A low-pass filter circuit; the low-pass filter circuit is embedded in the current mirror and is used to filter out high-frequency ripples and noise in the control signal;

[0025] A dynamic bias circuit; the input end of the dynamic bias circuit is electrically connected to the source follower and the current mirror, and the output end is electrically connected to the gate of the power transistor, and is used to dynamically adjust the bias current of the power transistor according to changes in the control signal;

[0026] A shunt feedback circuit; the output end of the shunt feedback circuit is electrically connected to the source follower, and the output end is electrically connected to the gate of the power transistor, and is used to reduce the output impedance of the control signal by providing a negative feedback mechanism.

[0027] Optionally, the current mirror comprises:

[0028] A PMOS current mirror, used for reducing positive ripple and noise in the positive control signal by current replication; the low-pass filter circuit is embedded in the PMOS current mirror;

[0029] NMOS current mirror used to reduce negative ripple and noise in negative control signals by current replication.

[0030] Optionally, the PMOS current mirror includes a first PMOS tube, a second PMOS tube, and a third PMOS tube; the gate of the first PMOS tube is electrically connected to the gate of the second PMOS tube; the second PMOS tube is electrically connected to the third PMOS tube through the low-pass filter circuit; the first PMOS tube, the second PMOS tube, and the third PMOS tube are all electrically connected to the input voltage terminal.

[0031] Optionally, the NMOS current mirror includes a first NMOS tube and a second NMOS tube, a gate of the first NMOS tube is electrically connected to a gate of the second NMOS tube, and a drain of the first NMOS tube is electrically connected to a drain of the second NMOS tube.

[0032] Optionally, the error amplifier comprises:

[0033] an input circuit for receiving and comparing a feedback voltage from the resistor feedback network with a reference voltage of the bandgap reference source, and generating a voltage difference signal;

[0034] A gain circuit, used to amplify the voltage difference signal provided by the input circuit;

[0035] An output circuit, used for generating and outputting a control signal based on the voltage difference signal;

[0036] A power supply circuit, used for providing power to the error amplifier;

[0037] The feedback loop is used to adjust the stability and response speed of the error amplifier through a feedback mechanism.

[0038] In a second aspect, an embodiment of the present invention provides a power management circuit, comprising the aforementioned low voltage dropout linear regulator.

[0039] Compared with the traditional low-dropout linear regulator, the low-dropout linear regulator in the embodiment of the utility model breaks through the limitation of the traditional technical concept of reverse cancellation, and adopts the impedance attenuation buffer with simple circuit structure and low power consumption, and suppresses the high and low frequency ripple and noise in the control signal in a forward attenuation manner at the output end of the error amplifier, thereby improving the clarity and reliability of the signal, reducing the output impedance of the control signal, realizing smooth processing of the control signal, and ensuring low ripple and high precision of the output voltage. Furthermore, not only the circuit structure is simplified and the power consumption is reduced, but also the power supply rejection ratio (PSRR) value of the low-dropout linear regulator is significantly improved within a wide frequency range, and the power supply noise suppression capability is enhanced.

[0040] Therefore, the low-voltage difference linear regulator and power management circuit in the embodiment of the utility model not only have a simple circuit structure and low power consumption, which reduces power consumption, but also significantly improve the power supply rejection ratio (PSRR) value of the low-voltage difference linear regulator within a wide frequency range, enhance the power supply noise suppression capability, and are suitable for various electronic devices or systems that have strict requirements on power supply stability and noise levels, such as portable devices, wireless communication equipment, medical instruments, precision instruments, high-precision data acquisition systems, and power-sensitive analog circuits. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0042] Figure 1 A schematic circuit block diagram of a low voltage dropout linear regulator in an embodiment of the utility model is shown;

[0043] Figure 2 A schematic circuit block diagram of a low voltage drop linear regulator with a voltage stabilizing circuit in an embodiment of the utility model is shown;

[0044] Figure 3 A circuit diagram of an impedance attenuation buffer in an embodiment of the utility model is shown;

[0045] Figure 4 A schematic circuit block diagram of a power management circuit in an embodiment of the utility model is shown.

[0046] The corresponding relationship between the reference numerals and component names in the figures is as follows:

[0047] Power management circuit 10, low voltage dropout linear regulator 100, input voltage terminal 110, output voltage terminal 120, bandgap reference source 130, resistor feedback network 140, error amplifier 150, power transistor 160, impedance attenuation buffer 170, source follower 171, PMOS current mirror 172, NMOS current mirror 173, low-pass filter circuit 174, shunt feedback circuit 175, voltage stabilization circuit 180. DETAILED DESCRIPTION

[0048] In order to make the purpose, technical solution and advantages of the embodiment of the utility model clearer, the technical solution in the embodiment of the utility model will be clearly and completely described below in combination with actual application and with reference to the drawings of the embodiment of the utility model. Obviously, the described embodiment is a part of the embodiment of the utility model, not all the embodiments. Based on the embodiment of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0049] The low voltage drop linear regulator and power management circuit in the embodiment of the utility model are suitable for low noise, high precision power supply applications that are sensitive to noise, such as powering digital, analog or radio frequency chips of various electronic devices. Applications include but are not limited to portable devices, wireless communication equipment, medical instruments, precision instruments, high precision data acquisition systems, and power sensitive analog circuits.

[0050] The existing technical solution of low voltage difference linear regulator to improve power supply rejection ratio by replicating input ripple at the gate of power transistor has technical problems of complex circuit structure and high power consumption.

[0051] The inventors have conducted in-depth research and found that the reason why the existing low-dropout linear regulator has a complex circuit structure and high power consumption is not because a complex circuit with high power consumption must be used to completely eliminate the ripple at the output voltage end, but because the traditional technical concept believes that copying and amplifying the reverse ripple signal of the feedback input at the gate of the power transistor is the most effective solution to eliminate the ripple at the output voltage end. This solution inevitably requires the use of complex circuits such as multi-stage feedforward amplifiers and summing amplifiers to amplify the signal, resulting in a complex circuit structure and high power consumption.

[0052] The inventors further discovered that the smoothness of the control signal is the decisive factor affecting the ripple at the output voltage end. The smoothness of the control signal can also be improved by attenuating the ripple component in the control signal.

[0053] In the process of implementing the technical solution in this practical embodiment, the inventor found that the smoothness of the control signal is not only related to the size of the ripple and noise therein, but also related to the output impedance of the control signal. If the ripple and noise in the control signal can be suppressed at the same time, the clarity and reliability of the signal can be improved, and the output impedance of the control signal can be reduced, the smoothness of the control signal can be effectively improved, thereby eliminating the ripple at the output voltage end.

[0054] Based on the above understanding, the inventor provides a low voltage drop linear regulator and power management circuit. This technical solution uses an impedance attenuation buffer with a simple circuit structure and low power consumption to efficiently smooth the control signal in a way that combines ripple suppression and output impedance reduction, thereby suppressing low and high frequency ripples and noise in the control signal.

[0055] The technical solution of the utility model will be described below in conjunction with the accompanying drawings and embodiments.

[0056] Figure 1 A schematic circuit block diagram of a low voltage dropout linear regulator in an embodiment of the utility model is shown.

[0057] Now refer to Figure 1 As shown, in an embodiment of the utility model, a low voltage drop linear regulator is provided, which is applied to a power management circuit; the low voltage drop linear regulator comprises:

[0058] An input voltage terminal, used for receiving a fluctuating input voltage;

[0059] Output voltage terminal, used for outputting a stable output voltage;

[0060] A bandgap reference source, electrically connected to the input voltage terminal, for providing a reference voltage;

[0061] A resistor feedback network; an input end of the resistor feedback network is electrically connected to the output voltage end, and is used to provide a feedback voltage;

[0062] An error amplifier; a power supply terminal of the error amplifier is electrically connected to the input voltage terminal, a positive input terminal is electrically connected to the output terminal of the bandgap reference source, and receives a reference voltage from the bandgap reference source; a negative input terminal is electrically connected to the output terminal of the resistor feedback network, and receives a feedback voltage from the resistor feedback network; the error amplifier is used to generate and output a control signal based on a difference between a feedback voltage and a reference voltage;

[0063] An impedance attenuation buffer; the power supply end of the impedance attenuation buffer is electrically connected to the input voltage end, and the input end is electrically connected to the output end of the error amplifier, and is used to smooth the control signal transmitted from the error amplifier;

[0064] A power transistor; the source of the power transistor is electrically connected to the input voltage terminal, the gate is electrically connected to the output terminal of the impedance attenuation buffer, and the drain is electrically connected to the output voltage terminal; the power transistor is used to adjust the degree of conduction based on the smoothed control signal and output a stable voltage.

[0065] The embodiment of the utility model decomposes the technical function of eliminating the ripple of the output voltage into: generating a control signal, smoothing the control signal, and outputting a stable voltage according to the smoothed control signal.

[0066] The control signal generation function is realized as follows: a stable reference voltage is provided to the error amplifier through the bandgap reference source, and a feedback voltage for adjusting the output voltage is provided to the error amplifier through the resistor feedback network; the error amplifier generates a control signal based on the difference between the feedback voltage and the reference voltage.

[0067] The function of smoothing the control signal is realized as follows: at the output end of the error amplifier, the impedance attenuation buffer performs positive attenuation on the high and low frequency ripples and noise in the received control signal, thereby improving the clarity and reliability of the signal, and reducing the output impedance of the control signal, thereby achieving smooth processing of the control signal.

[0068] The function of outputting a stable voltage according to the smoothed control signal is realized as follows: the power transistor adjusts the degree of conduction according to the smoothed control signal, outputs a stable voltage, and eliminates the ripple at the output voltage end.

[0069] Through the above technical means, the limitations of the traditional technical concept of reverse cancellation are broken, and the control signal is smoothed by combining ripple and noise forward attenuation and output impedance reduction. Forward attenuation can not only suppress low-frequency ripple, but also suppress high-frequency ripple. Then, using an impedance attenuation buffer with a simple circuit structure and low power consumption, ripple and noise suppression in the control signal is achieved within a wide frequency range, and the output impedance that affects the smoothness of the control signal is reduced, which significantly improves the power supply rejection ratio (PSRR) value of the low-dropout linear regulator and enhances the power supply noise suppression capability.

[0070] In an embodiment of the utility model, the input voltage terminal is used to receive a fluctuating input voltage and provide it to the bandgap reference source, the error amplifier, and the impedance attenuation buffer as an operating voltage, and to the power transistor as a voltage to be regulated.

[0071] In the embodiment of the utility model, the output voltage terminal is electrically connected to the load and is used to output a stable output voltage;

[0072] In an embodiment of the utility model, the bandgap reference source is electrically connected to the input voltage terminal, and is used to provide a reference voltage serving as a comparison reference to the error amplifier.

[0073] Specifically, the bandgap reference source is usually made of silicon-based materials, and through precise doping and manufacturing processes, a PN structure with an energy gap is formed. This PN structure can utilize the bandgap characteristics of semiconductors to generate a reference voltage that does not change with temperature.

[0074] In an embodiment of the utility model, the input end of the resistor feedback network is electrically connected to the output voltage end; the resistor feedback network is composed of at least two resistors, and the constituent resistors are connected in a specific ratio to generate a voltage drop proportional to the output voltage. The voltage drop is sent to the negative input end of the error amplifier and compared with the reference voltage provided by the bandgap reference source to generate a control signal.

[0075] Specifically, the resistors constituting the resistor feedback network are usually made of metal film or carbon film materials, and have high precision and low temperature coefficient characteristics, thereby ensuring the accuracy of voltage distribution.

[0076] In an embodiment of the utility model, the error amplifier is used to generate and output a control signal based on the difference between the feedback voltage and the reference voltage, and the control signal is used to adjust the conduction degree of the power transistor to maintain a stable voltage output. Specifically, the error amplifier includes a high gain circuit, which can quickly respond to voltage changes, amplify the voltage difference signal, and generate an accurate control signal.

[0077] In an embodiment of the utility model, the impedance attenuation buffer is embedded in the connection circuit between the error amplifier and the power transistor, and is used to smooth the control signal transmitted from the error amplifier, improve the clarity and reliability of the control signal, and then transmit it to the power transistor; wherein the impedance attenuation buffer is composed of multiple passive components, such as capacitors and inductors, or PMOS tubes and NMOS tubes, which work together to adopt a forward attenuation method to suppress high and low frequency ripples in the control signal, and reduce the output impedance in the control signal, thereby achieving smooth processing of the control signal.

[0078] In the embodiment of the utility model, the source of the power transistor is electrically connected to the input voltage terminal to form a basic input-output path of the low voltage difference linear regulator.

[0079] Exemplarily, the power transistor is usually a PMOS tube or a bipolar transistor, which has high current and high power handling capabilities, can quickly respond to control signals, adjust output voltage, and achieve stable voltage output. The selection of the power transistor needs to take into account on-resistance, switching speed, and thermal performance to ensure reliable operation under different load and temperature conditions.

[0080] In an embodiment of the utility model, the input voltage end transmits the fluctuating input voltage to the power transistor through the source of the power transistor. The power transistor adjusts the degree of conduction based on the smoothed control signal, and stabilizes the fluctuating input voltage received by the source to ensure the stability of the output voltage and the minimization of the ripple.

[0081] The working process of the low voltage drop linear regulator in the embodiment of the utility model is as follows:

[0082] The input voltage terminal receives the fluctuating input voltage and transmits it to the source of the power transistor;

[0083] The bandgap reference source provides a stable reference voltage for the error amplifier, the resistor feedback network provides a feedback voltage for adjusting an output voltage for the error amplifier, and the error amplifier generates a control signal based on a difference between the feedback voltage and the reference voltage.

[0084] At the output end of the error amplifier, the impedance attenuation buffer performs forward attenuation on high- and low-frequency ripples and noise in the received control signal, reduces the output impedance of the control signal, improves the smoothness of the control signal, and then outputs it to the power transistor;

[0085] The fluctuating input voltage transmitted through the source of the power transistor is output as a stable voltage through the drain under the control of the power transistor adjusting its conduction state according to the smoothed control signal, thereby achieving low ripple and high precision of the output voltage. Specifically, when the output voltage is higher than the set value, the error amplifier will generate a reduced control signal, the impedance attenuation buffer will reduce the ripple and noise in the control signal and reduce the output impedance of the control signal, the conduction state of the power transistor will be reduced, and the output voltage will be reduced. Conversely, the output voltage will be pulled up. Through this negative feedback mechanism, the output voltage can be locked and maintained at the set value. Furthermore, the impedance attenuation buffer with a simplified circuit structure and low power consumption is adopted, and the value of the power supply rejection ratio (PSRR) of the low voltage difference linear regulator is significantly improved within a wide frequency range, and the power supply noise suppression capability is enhanced.

[0086] Traditional low-dropout linear regulators rely on multiple feedforward amplifiers and summing amplifiers in the power transistor to replicate the reverse input ripple at the gate of the power transistor, reduce the control signal gain through reverse cancellation, and achieve smooth processing of the control signal.

[0087] Compared with the traditional low-dropout linear regulator, the low-dropout linear regulator in the embodiment of the utility model breaks through the limitation of the traditional technical concept of reverse cancellation, and adopts the impedance attenuation buffer with simple circuit structure and low power consumption, and suppresses the high and low frequency ripple and noise in the control signal in a forward attenuation manner at the output end of the error amplifier, thereby improving the clarity and reliability of the signal, reducing the output impedance of the control signal, realizing smooth processing of the control signal, and ensuring low ripple and high precision of the output voltage. Furthermore, not only the circuit structure is simplified and the power consumption is reduced, but also the power supply rejection ratio (PSRR) value of the low-dropout linear regulator is significantly improved within a wide frequency range, and the power supply noise suppression capability is enhanced.

[0088] Therefore, the low voltage dropout linear regulator in the embodiment of the utility model not only has a simple circuit structure and low power consumption, which reduces power consumption, but also significantly improves the power supply rejection ratio (PSRR) value of the low voltage dropout linear regulator within a wide frequency range, thereby enhancing the ability to suppress power supply noise. It is suitable for various electronic devices or systems that have strict requirements on power supply stability and noise levels, such as portable devices, wireless communication equipment, medical instruments, precision instruments, high-precision data acquisition systems, and power-sensitive analog circuits.

[0089] The working voltage of the error amplifier is a fluctuating input voltage provided by the input voltage terminal. The fluctuating input voltage is used as the working voltage of the error amplifier, which causes the control signal generated by the error amplifier to have more ripples and noise.

[0090] Figure 2The schematic circuit block diagram of the low voltage drop linear regulator with voltage stabilization circuit in the embodiment of the utility model is shown. Figure 2 As shown:

[0091] In order to eliminate the influence of the fluctuation of the input voltage transmitted through the input voltage terminal, optionally, the low voltage dropout linear regulator further includes:

[0092] The voltage stabilizing circuit is embedded between the input voltage terminal and the error amplifier and is used to provide a stable operating voltage for the error amplifier.

[0093] In an embodiment of the utility model, the fluctuating voltage input to the input voltage terminal is stabilized by the external voltage stabilizing circuit, so as to provide a stable operating voltage for the error amplifier, reduce the ripple and noise in the control signal generated by the error amplifier, and improve the purity of the control signal.

[0094] Figure 3 A circuit diagram of an impedance attenuation buffer in an embodiment of the utility model is shown.

[0095] Now refer to Figure 3 As shown, in Figure 3 In the embodiment, the impedance attenuation buffer is composed of a source follower, a PMOS current mirror, an NMOS current mirror, a low-pass filter circuit, a dynamic bias circuit (not indicated), and a shunt feedback circuit; wherein the source follower is composed of a PMOS tube Mp1; the PMOS current mirror is composed of a first PMOS tube Mp2, a second PMOS tube Mp3, and a third PMOS tube Mp4; the NMOS current mirror is composed of a first NMOS tube Mn2 and a second NMOS tube Mn3; the low-pass filter is composed of a PMOS tube Mp5, a PMOS tube Mp6, an NMOS tube Mn4, and a capacitor C; the dynamic bias circuit is composed of a PMOS tube Mp8 and a PMOS tube Mp9; the shunt feedback circuit is composed of an NMOS tube Mn1; and the PMOS current mirror and the NMOS current mirror together constitute a current mirror.

[0096] To ensure that the impedance attenuation buffer has a good control signal smoothing processing capability, optionally, the impedance attenuation buffer includes:

[0097] A source follower, electrically connected to the output end of the error amplifier, for receiving a control signal from the error amplifier and reducing an output impedance of the control signal;

[0098] A current mirror; the input end of the current mirror is electrically connected to the output end of the source follower, and is used to attenuate the ripple and noise in the control signal transmitted from the source follower through an internal impedance;

[0099] A low-pass filter circuit; the low-pass filter circuit is embedded in the current mirror and is used to filter out high-frequency ripples and noise in the control signal;

[0100] A dynamic bias circuit; the input end of the dynamic bias circuit is electrically connected to the source follower and the current mirror, and the output end is electrically connected to the gate of the power transistor, and is used to dynamically adjust the bias current of the power transistor according to changes in the control signal;

[0101] A shunt feedback circuit; the output end of the shunt feedback circuit is electrically connected to the source follower, and the output end is electrically connected to the gate of the power transistor, and is used to reduce the output impedance of the control signal by providing a negative feedback mechanism.

[0102] In an embodiment of the utility model, the source follower is electrically connected to the output end of the error amplifier, and is used to receive a control signal and reduce its output impedance, thereby reducing the load effect on subsequent circuits; specifically, the source follower is usually composed of one or more transistors, and is configured to provide a low-impedance signal source, so as to reduce its output impedance after receiving the control signal while maintaining the integrity of the control signal.

[0103] In the embodiment of the utility model, the input end of the current mirror is electrically connected to the output end of the source follower, and is used to attenuate the high and low frequency ripples and noise in the control signal transmitted from the source follower through internal impedance; the current mirror is composed of specific semiconductor devices, such as PMOS and NMOS tubes, which can accurately replicate the current at the output end of the source follower to achieve the attenuation of ripples and noise in the control signal. In practical applications, the current mirror can adopt a differential pair structure to provide high impedance input and low impedance output, and enhance the stability of the control signal.

[0104] In an embodiment of the utility model, the low-pass filter circuit is embedded in the current mirror to filter out high-frequency ripples and noise in the control signal, thereby improving the clarity and reliability of the control signal. The low-pass filter circuit is usually composed of a resistor in series and a capacitor in parallel, or it can be composed of a capacitor and a PMOS tube, which allows low-frequency signal components to pass through while suppressing high-frequency components above a specific cutoff frequency. The low-pass filter circuit needs to consider the selection of the cutoff frequency to ensure that the high-frequency components in the control signal can be effectively filtered out without affecting the DC component of the signal.

[0105] In an embodiment of the utility model, the dynamic bias circuit has an input end electrically connected to the source follower and the current mirror, and an output end connected to the gate of the power transistor, and is used to dynamically adjust the bias current of the power transistor according to changes in the control signal, optimize the working state of the power transistor, and adapt to different working conditions.

[0106] In the embodiment of the utility model, the output end of the shunt feedback circuit is electrically connected to the source follower and to the gate of the power transistor, and is used to reduce the output impedance of the control signal by providing a negative feedback mechanism while maintaining the stability of the signal. The negative feedback mechanism not only improves the stability of the impedance attenuation buffer, but also helps to reduce power consumption.

[0107] In the embodiment of the utility model, the impedance attenuation buffer has good performance in a high-frequency environment. It can not only reduce the high- and low-frequency ripples and noise in the control signal and improve the clarity and reliability of the signal, but also reduce the output impedance of the control signal, and can dynamically adjust the bias current of the power transistor according to actual conditions to optimize the performance of the power transistor and effectively reduce power consumption.

[0108] In order to effectively suppress both positive and negative ripples and noise in the control signal, optionally, the current mirror includes:

[0109] A PMOS current mirror, used to reduce positive ripple and noise in the positive control signal by current replication; the low-pass filter circuit is embedded in the PMOS current mirror;

[0110] NMOS current mirror used to reduce negative ripple and noise in negative control signals by current replication.

[0111] In the embodiment of the utility model, the PMOS current mirror is composed of a plurality of PMOS transistors, and through precise matching and configuration, the input current is accurately copied, and the positive ripple and noise in the positive control signal are reduced. The low-pass filter circuit embedded in the PMOS current mirror can completely filter out the high-frequency ripple and noise in the positive control signal, ensuring the purity of the signal during the current copying process.

[0112] In the embodiment of the utility model, the NMOS current mirror is composed of a plurality of NMOS transistors, and through precise matching and configuration, accurate replication of the input current is achieved, thereby reducing negative ripple and noise in the negative control signal.

[0113] In the embodiment of the utility model, the PMOS current mirror, the low-pass filter circuit and the NMOS current mirror work together to ensure that both positive and negative ripples and noise can be effectively attenuated, that is, the power supply rejection ratio (PSRR) value is significantly improved through bidirectional processing, and the resistance to input voltage fluctuations is enhanced. At the same time, the high-frequency components in the control signal are completely filtered out by the low-pass filter circuit, thereby ensuring that the low-dropout linear regulator has good performance and stability in a high-frequency environment.

[0114] In order to ensure that the positive ripple and noise in the positive control signal are effectively attenuated through precise current replication, optionally, the PMOS current mirror includes a first PMOS tube, a second PMOS tube, and a third PMOS tube; the gate of the first PMOS tube is electrically connected to the gate of the second PMOS tube; the second PMOS tube is electrically connected to the third PMOS tube through the low-pass filter circuit; the first PMOS tube, the second PMOS tube, and the third PMOS tube are all electrically connected to the input voltage terminal.

[0115] In an embodiment of the utility model, the gate of the first PMOS tube is electrically connected to the gate of the second PMOS tube, and the second PMOS tube is electrically connected to the third PMOS tube through the low-pass filter circuit, forming a basic path for current replication, ensuring that high- and low-frequency positive ripples and noise in the positive control signal can be effectively attenuated to achieve smooth processing of the positive control signal; on this basis, the low-pass filter circuit is embedded between the second PMOS tube and the third PMOS tube, so that when the second PMOS tube replicates the current of the first PMOS tube, the high-frequency ripples and noise in the positive control signal are directly filtered out through the low-pass filter circuit, thereby improving the purity of the positive control signal, so as to facilitate the third PMOS tube to further smooth the quality of the control signal processed by the second PMOS tube.

[0116] Obviously, the PMOS current mirror can not only effectively attenuate the high and low frequency positive ripples and noise in the positive control signal, but also completely remove the high positive ripples and noise from the positive control signal, thereby improving the purity of the positive control signal, thereby ensuring good performance and stability in a high frequency environment.

[0117] In order to ensure that the negative ripple and noise in the negative control signal are effectively attenuated through precise current replication, optionally, the NMOS current mirror includes a first NMOS tube and a second NMOS tube, the gate of the first NMOS tube is electrically connected to the gate of the second NMOS tube, and the drain of the first NMOS tube is electrically connected to the drain of the second NMOS tube.

[0118] In an embodiment of the utility model, the gate of the first NMOS tube and the gate of the second NMOS tube are electrically connected to form a basic path for current replication, ensuring that high- and low-frequency negative ripples and noise in the negative control signal can be effectively attenuated, thereby achieving smooth processing of the negative control signal; and, during the current replication process, the first NMOS tube and the second NMOS tube both receive the same control signal to achieve signal synchronization, ensuring that the behaviors of the two transistors are accurately matched during the current replication process, and the drain of the first NMOS tube and the drain of the second NMOS tube are electrically connected to ensure the consistency of the output current, thereby maintaining the stability of the control signal.

[0119] In order to improve the working stability of the error amplifier, optionally, the error amplifier includes:

[0120] an input circuit for receiving and comparing a feedback voltage from the resistor feedback network with a reference voltage of the bandgap reference source, and generating a voltage difference signal;

[0121] A gain circuit, used to amplify the voltage difference signal provided by the input circuit;

[0122] An output circuit, used for generating and outputting a control signal based on the voltage difference signal;

[0123] A power supply circuit, used for providing power to the error amplifier;

[0124] The feedback loop is used to adjust the stability and response speed of the error amplifier through a feedback mechanism.

[0125] In an embodiment of the utility model, the error amplifier can automatically adjust the operating voltage according to the change of the input voltage through the built-in feedback loop. In this way, the error amplifier can not only accurately detect and amplify the voltage difference signal, but also effectively reduce the ripple and noise in the control signal generated by the error amplifier, thereby improving the purity of the control signal.

[0126] Figure 4 A schematic circuit block diagram of a power management circuit in an embodiment of the utility model is shown.

[0127] Now refer to Figure 4 As shown, an embodiment of the utility model provides a power management circuit, including the aforementioned low voltage drop linear regulator.

[0128] It should be understood that the low-voltage dropout linear regulator in the embodiment of the power management circuit of the present invention is the low-voltage dropout linear regulator in the aforementioned embodiment of the low-voltage dropout linear regulator of the present invention. The description of the low-voltage dropout linear regulator in the embodiment of the power management circuit of the present invention can refer to the relevant description in the embodiment of the low-voltage dropout linear regulator, and will not be repeated here.

[0129] In the embodiment of the utility model, the power management circuit is a low-noise, high-precision power management circuit, which is suitable for various electronic devices or systems that have strict requirements on power supply stability and noise levels, such as portable devices, wireless communication equipment, medical instruments, precision instruments, high-precision data acquisition systems, and power-sensitive analog circuits.

Claims

1. Low voltage dropout linear regulator, used in power management circuit; characterized in that, The low dropout linear regulator comprises: An input voltage terminal, used for receiving a fluctuating input voltage; Output voltage terminal, used for outputting a stable output voltage; A bandgap reference source, electrically connected to the input voltage terminal, for providing a reference voltage; A resistor feedback network; an input end of the resistor feedback network is electrically connected to the output voltage end, and is used to provide a feedback voltage; An error amplifier; a power supply terminal of the error amplifier is electrically connected to the input voltage terminal, a positive input terminal is electrically connected to the output terminal of the bandgap reference source, and receives a reference voltage from the bandgap reference source; a negative input terminal is electrically connected to the output terminal of the resistor feedback network, and receives a feedback voltage from the resistor feedback network; the error amplifier is used to generate and output a control signal based on a difference between a feedback voltage and a reference voltage; An impedance attenuation buffer; the power supply end of the impedance attenuation buffer is electrically connected to the input voltage end, and the input end is electrically connected to the output end of the error amplifier, and is used to smooth the control signal transmitted from the error amplifier; A power transistor; the source of the power transistor is electrically connected to the input voltage terminal, the gate is electrically connected to the output terminal of the impedance attenuation buffer, and the drain is electrically connected to the output voltage terminal; the power transistor is used to adjust the degree of conduction based on the smoothed control signal and output a stable voltage.

2. The low voltage dropout linear regulator according to claim 1, characterized in that: The low dropout linear regulator further comprises: The voltage stabilizing circuit is embedded between the input voltage terminal and the error amplifier and is used to provide a stable operating voltage for the error amplifier.

3. The low voltage dropout linear regulator according to claim 1 or 2, characterized in that: The impedance attenuation buffer comprises: A source follower, electrically connected to the output end of the error amplifier, for receiving a control signal from the error amplifier and reducing an output impedance of the control signal; A current mirror; the input end of the current mirror is electrically connected to the output end of the source follower, and is used to attenuate the ripple and noise in the control signal transmitted from the source follower through an internal impedance; A low-pass filter circuit; the low-pass filter circuit is embedded in the current mirror and is used to filter out high-frequency ripples and noise in the control signal; A dynamic bias circuit; the input end of the dynamic bias circuit is electrically connected to the source follower and the current mirror, and the output end is electrically connected to the gate of the power transistor, and is used to dynamically adjust the bias current of the power transistor according to changes in the control signal; A shunt feedback circuit; the output end of the shunt feedback circuit is electrically connected to the source follower, and the output end is electrically connected to the gate of the power transistor, and is used to reduce the output impedance of the control signal by providing a negative feedback mechanism.

4. The low voltage dropout linear regulator according to claim 3, characterized in that: The current mirror comprises: A PMOS current mirror, used for reducing positive ripple and noise in the positive control signal by current replication; the low-pass filter circuit is embedded in the PMOS current mirror; NMOS current mirror used to reduce negative ripple and noise in negative control signals by current replication.

5. The low voltage dropout linear regulator according to claim 4, characterized in that: The PMOS current mirror includes a first PMOS tube, a second PMOS tube, and a third PMOS tube; the gate of the first PMOS tube is electrically connected to the gate of the second PMOS tube; the second PMOS tube is electrically connected to the third PMOS tube through the low-pass filter circuit; the first PMOS tube, the second PMOS tube, and the third PMOS tube are all electrically connected to the input voltage terminal.

6. The low voltage dropout linear regulator according to claim 4, characterized in that: The NMOS current mirror includes a first NMOS tube and a second NMOS tube, a gate of the first NMOS tube is electrically connected to a gate of the second NMOS tube, and a drain of the first NMOS tube is electrically connected to a drain of the second NMOS tube.

7. The low voltage dropout linear regulator according to claim 1 or 2, characterized in that: The error amplifier comprises: an input circuit for receiving and comparing a feedback voltage from the resistor feedback network with a reference voltage of the bandgap reference source, and generating a voltage difference signal; A gain circuit, used to amplify the voltage difference signal provided by the input circuit; An output circuit, used for generating and outputting a control signal based on the voltage difference signal; A power supply circuit, used for providing power to the error amplifier; The feedback loop is used to adjust the stability and response speed of the error amplifier through a feedback mechanism.

8. A power management circuit, characterized in that: A low voltage drop linear regulator comprising any one of claims 1 to 7.

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